E. J. Russell and E. H. Richards 499 



Experiments with manure heaps show that results similar to those 

 of the laboratory are not obtained in manure heaps, but that on the 

 contrary both nitrogen and ammonia are lost. Improvements can be 

 made by compacting and by sheltering the heap ; even a little shelter 

 is good. But at best the heap is an imperfect method, and probably 

 in the best practice it has been developed about as far as it can go. 



Our results indicate that the main hope for further improvement 

 lies in storing manure in water-tight pits or tanks so arranged as to 

 allow of the attainment of anaerobic conditions and suitable tempera- 

 ture. Whether the improvement would be profitable could only be 

 settled by trial ; it paid in the case of silage, however, and the silo made 

 of reinforced concrete has displaced the old stack silo because it was 

 found more profitable. 



The Hon. Rupert Guinness has kindly given us facilities for carrying 

 out the necessary large scale trials on his farm at Hoebridge. 



Historical. 



In order to see the problem as a whole it is necessary to go somewhat 

 into the history of the art and science of managing the manure heap. 

 We shall not do this in any detail, although in point of fact an exceed- 

 ingly interesting account might be written showing how, at every stage, 

 the best practice has been in accordance with current scientific ideas, 

 while ordinary practice has lagged behind for want of means to carry 

 out what was known to be best. 



The management of the manure heap had already reached an 

 advanced stage of development in Roman times. Varro^ writing about 

 40 B.C. insists upon two points ; first, that the manure should be rotted 

 before use and therefore there should be two heaps, — one fresh, and 

 one rotted; secondly, that the heap should be kept moist by allowing 

 water to run into it and also by protecting its sides from the sun by 

 twigs and leaves, "for the sun must not suck out beforehand the good- 

 ness which the earth requires." Columella, about 90 A.D., as usual 

 amplifies Varro, and gives details for constructing the place . or pit 

 where the manure is to be kept^, and for turning the manure in summer 

 time to facilitate rotting : this rotted manure was needed for the corn, 

 while the stronger fresh manure was used for grass. He suggested 



^ Varro, Rerum Rusticarum, lib. i. cap. 13. 



2 Columella, Rerum Rusticarum, lib. ii. cap. 15 : "With bottom shelving in the manner 

 of ponds, well built and paved, that the moistmre shall not pass through, for it is of great 

 importance that the dung retain its strength by the juice of it not being dried up." 

 Journ. of Agric. Sci. vni 33 



